Evaluation of bactericidal efficacy of modified TiO₂ nanoparticles via combined hydrogen peroxide and blue light irradiation.

Abstract

Purpose: The present study evaluated the enhanced antibacterial efficacy against Enterococcus faecalis (E. faecalis) of modified titanium dioxide (TiO₂) nanoparticles when combined with hydrogen peroxide (HP) and blue light irradiation.

Methods: Commercial pure TiO₂ was modified with polymer and copper to create polymer-copper-TiO₂ (pvpCT) nanoparticles. The optical property of pvpCT was characterized by absorbance measurements. Radical production was spectroscopically assayed using methylene blue (MB) degradation and terephthalic acid (TA) fluorescence. The antibacterial efficacy was then assessed against E. faecalis under blue light irradiation.

Results: Unlike pure TiO₂, pvpCT exhibited a distinct absorbance after 400 nm and presented a dark yellow visual appearance, indicating successful modification. The combined treatment of pvpCT, HP, and 405 nm laser irradiation resulted in significantly higher MB degradation and a strong fluorescence peak near 425 nm from the TA assay, outperforming HP-only (up to 15%) or laser-only treatments. Crucially, this synergistic condition (pvpCT+HP+blue light irradiation) also achieved a remarkable elimination of E. faecalis. These findings suggest that the combination of pvpCT, HP, and blue light irradiation represents a promising and effective strategy for advanced antibacterial treatment in dental applications.

Clinical significance: Combined treatment of the polymer-combined-copper-coupled TiO₂, hydrogen peroxide, and blue laser irradiation can effectively eliminate oral bacteria, E. faecalis, through the reaction of hydroxyl radicals.